Oratory in the House and Senate has dropped a full grade, to the high school sophomore level, an analysis finds.

WASHINGTON — — If it sounds like the debates in Congress have devolved into those of teenagers, it's because they have.

Discourse in the House and Senate has dropped a full grade level — to the equivalent of high school sophomore, according to a new study.

Call this the dumbing down of Congress in a partisan age. Or a shift to plain-spoken populism ignited by the new class of tea party Republicans.

But what has become clear in the new research is that the soaring oratory that once filled the floors of the House and Senate with million-dollar diction and sophisticated syntax is making way for a more modest approach.

"Congress is changing as an institution, and what you see is more and more members gearing their speeches as sound bites or YouTube clips," said Lee Drutman, a senior fellow at the nonpartisan Sunlight Foundation, which compiled the study released Monday.

"You can [hark] back to a golden age of Congress when members quoted Shakespeare on the floor and really engaged in debate and talked to each other and tried to reason back and forth," he said.

Consider Everett M. Dirksen, the legendary Republican senator from Illinois, who defended a civil rights bill in 1964 by paraphrasing 19th century French writer Victor Hugo: "Stronger than all the armies is an idea whose time has come."

But that was then.

In an analysis of floor debates over the last several years, the study found that newer lawmakers tended to speak at a lower grade level than the veterans of congressional speechifying.

And political moderates among both Republicans and Democrats tended to carry on at a higher grade level than those more partisan liberals or conservatives.

With that framework in mind, it should come as no surprise that the lawmakers at the bottom of the list, speaking at the lowest grade level, are among the most ardent tea party Republicans in the freshman class. Rep. Mick Mulvaney of South Carolina, Rep. Robert Woodall of Georgia and Sen. Rand Paul of Kentucky were the bottom three — speaking at about an eighth-grade level, the study found.

"We look at it as a badge of honor," said Mulvaney, a graduate of Georgetown University and the University of North Carolina Law School, who notes that he often speaks on the floor "extemporaneously."

"It's a conscious decision on my part. We are trying to be clear and trying to be concise," he added. He said he and his wife had been known to diagram sentences at the dinner table, a byproduct of having schoolteacher parents.

"I can explain the difference between 'fewer' and 'less,'" Mulvaney said, but he acknowledged that he still stumbled over the difference between "farther" and "further."

"I don't think people see the polysyllabic words — or the number of words — in a sentence as a sign of your intelligence," he said.

As a case in point, he cites fellow Republican Rep. Dan Lungren of Gold River, a seasoned politician who topped the list as the lawmaker with the highest level of speech — that of a college senior.

That makes Lungren almost a throwback — on par with the Federalist Papers (a 17.1 grade level) or the U.S. Constitution (17.8 grade level) — though it is not clear his speeches are easier to understand.

"The canard that somehow we are tearing the Constitution up just does not stand any kind of inquiry whatsoever," Lungren said during a debate over the Patriot Act. "The suggestion that somehow we are invading the civil liberties of citizens is negated by the language in the three sections of the bill that we have before us."

Californians ranked among the better spoken overall, and the No. 2 slot went to Rep.Lucille Roybal-Allard(D-East Los Angeles), at almost a 16th-grade level. Her skills were on display during last week's debate on a GOP version of the Violence Against Women Act that Democrats largely opposed.

"I cannot in good conscience vote to pass this version of VAWA, as it erases 18 years of bipartisan efforts to respond to the needs of victims of domestic violence," she said. "I am also disappointed that, yet again, provisions to alleviate the economic factors that keep victims in abusive relationships have not been included."

The best and worst speeches may be in the ear of the listener, and the study noted that President Obama's 2012 State of the Union address was judged by other researchers to rank at the eighth-grade level for the third year in a row.

As for those high-powered words from the Scholastic Assessment Test, memorized and recited by legions of high schoolers, they go virtually unspoken in Congress.

Of the 100 words on SAT preparation study lists, 14 are missing entirely from the Congressional Record for this Congress — notably "florid," "hackneyed," "ostentatious" and "querulous."

The most-used SAT word — "compromise" — was said the most by Sen. Harry Reid (D-Nev.), the majority leader, who is fond of declaring, "Legislation is the art of compromise."

But in this partisan environment, as the study noted, even saying the word 142 times "does not make it so."